Ghosts and flare are important indicators for camera quality evaluation, and are comprehensive manifestations of stray light on an image sensor in an imaging system. Formation of the stray light includes but is not limited to energy generated by a single time or multiple times of light reflection on an optical element, a mechanical structural element, or an image sensor. Ghosts and flare mean that bright rings, dots, flecks, or the like may easily appear on a photographed image when a user performs photographing towards a streetlight, morning sunshine, afternoon sunlight, or the setting sun, and the rings, dots, flecks, or the like are vividly referred to as ghosts and flare. Existence of ghosts and flare affects beauty of a picture.
Ghosts and flare are harmful to some extent. For example, in a high-power laser system, ghosts are formed after energy generated by specular reflection of light is concentrated, causing laser damage to a surface or an internal structure of a system element. Ghosts and flare also have artistry. For example, ghosts and flare are also relatively common in a photographic system. A superior-quality single-lens reflex camera can make full use of advantages of a system structure design and appropriately adjust a surface type, a thickness, and an aperture of a lens, a lens cone structure, and the like, so that ghosts and flare achieve optimum artistry. However, for a smart terminal with a compact structure, such as a mobile phone, a bright ring or dot on a picture spoils beauty of the picture. This problem annoys users.
In a design process of an optical system, causes of ghosts and flare usually need to be analyzed, and propagation paths of stray light need to be cut off in optical design and structural design, so as to achieve an optimum inhibition effect. However, for a camera system of a mobile phone, because a mobile phone is increasingly light and thin and has an extremely compact structure nowadays, space left for a camera system of the mobile phone is limited. In the camera system of the mobile phone with a compact structure, ghost and flare correction methods are limited; moreover, many products on the market have a problem of ghosts and flare to varying degrees. This becomes one of important factors that limit improvement of mobile-phone photographing quality.